In fact, the main saleroom was so packed that Profiles in History set up a satellite link to a neighbouring room.

It's estimated there were over 500 people present at the auction, with many thousands bidding via the internet.

A large percentage were new collectors, attracted to the memorabilia market by what was possibly the largest sales of the last 40 years.

Paul Fraser Collectibles was among the bidders, when the dress appeared on the auction block we opened the bidding at $1.1m.

We knew a chance to own this dress was a once-in-a-lifetime opportunity - it's arguably the most famous dress in all cinema history.

We stopped at $2m ($2.4m including commission) - that was our limit. Double the lower estimate. At that price we were confident of purchasing the dress.

Our reasoning was the comparable sale of Marilyn's Happy Birthday Mr President dress that sold for $1.15m in 1999.

Yet the bids still kept climbing. In fact, they shot up.

In total, bidding on this one auction lot lasted 20 minutes, and Debbie Reynolds herself was reportedly in tears.

In the end, the dress sold for $5.6m, including a cool $1m commission to the auction house.

The dress's $5.6m sale price is testament to how strong the celebrity collectibles market is - and also how the excitement of an iconographic piece can excite bidders and push up values.

For instance, had Paul Fraser Collectibles won The Seven Year Itch dress with our $2.4m bid and then offered it on the market for $5m... people would think that we were mad.

Yet, on the day, bidders in the Beverly Hill saleroom were on the cusp of pushing the dress's value to $6m.

Early reports say the overall sale figure for Debbie Reynolds' collection - also including Dorothy's ruby slippers from the Wizard of Oz and Audrey Hepburn's famous Ascot dress from My Fair Lady - was $18.6m.

The latter dress shows that Hepburn is still hot on Monroe's heels after all these years. In the end, it sold for $4.5m against its $200,000-300,000 pre-sale estimate.

And what makes the overall $18.6m sale total even more impressive is when you consider the origins of Reynolds' collection in the early 1970s....

"At the time, the people that owned the [Metro-Goldwyn-Mayer] studio decided they were interested in real estate, they weren't interested in any other memorabilia," said Debbie Reynolds in an interview with the BBC prior to the sale.

"They were really just throwing it away, all of the music went under the freeway..."

In fact, MGM sold the contents of seven sound stages for a mere $1.5m to auctioneer David Weisz in 1970. There were 350,000 costumes alone.

If MGM's executives could have known how much memorabilia investment values would grow in future years, they might have reconsidered...